One element voltage supply device

ABSTRACT

A one element voltage source which provides a voltage output of a polarity opposite from that applied to the input thereof includes a transistor having emitter, base and collector electrodes. A voltage of a first polarity is impressed across the emitter-base junction of the transistor to place the junction in an avalanched condition. Upon achieving such a condition, an opposite polarity voltage of a lesser magnitude is realized at the collector of the transistor. In one embodiment, the single element voltage source is used in conjunction with a silicon controlled rectifier (SCR) as a voltage regulator device for use in the electrical generating system of an automotive vehicle.

Lace

Jan. 28, 1975 ONE ELEMENT VOLTAGE SUPPLY DEVICE Inventor: Melvin A. Lace, Prospect Heights,

lll.

Assignee: M0t0r0lalnc., Chicago, lll.

Filed: Sept. 13, 1973 Appl. No.: 397,023

US. Cl 322/28, 320/39, 320/64, 320/DlG. 1

Int. Cl. M02] 7/16 Field of Search 322/28, 25; 320/64, 68, 320/39, DlG. 1; 307/283, 302

References Cited UNITED STATES PATENTS 2/1973 Lace 322/28 X Primary Examiner-J. D. Miller Assistant Examiner-Robert J. Hickey Attorney, Agent, or FirmDonald 1. Lisa; Vincent J. Rauner [57] ABSTRACT A one element voltage source vvhich provides a voltage output ofa polarity opposite from that applied to the input thereof includes a transistor having emitter, base and collector electrodes. A voltage of a first polarity is impressed across the emitter-base junction of the transistor to place the junction in an avalanched condition. Upon achieving such a condition, an opposite polarity voltage of a lesser magnitude is realized at the collector of the transistor. In one embodiment, the single element voltage source is used inconjunction with a silicon controlled rectifier (SCR) as a voltage regulator device for use in the electrical generating system of an automotive vehicle.

3 Claims, 2 Drawing Figures I ONE ELEMENT VOLTAGE SUPPLY DEVICE BACKGROUND ularly to the use of such apparatus in specific applicatrons.

Apparatus for providing a voltage output for use in controlling the operation of other devices or apparatus is known in the art. Voltage producing apparatus which provides an output voltage of one polarity and which is powered by an input voltageof an opposite polarity, is

also known in the prior art. This last-mentioned type of apparatus normally includes, however, several elements or components for making the transformation. Thus, the fabrication of the apparatus includes the provision of the plurality of elements required therein and the assembly of the elements in a proper manner. The latter thus increases thecost of the apparatus.

SUMMARY It is therefore an object of the present invention to provide apparatus including a single element which produces a potential opposite from that applied thereto which can be utilized constructively and the cost of which is relatively small.

It is another object of the present invention to provide a method for producing a voltage potential at the output electrode of the transistor which is of a polarity opposite from that applied at the. input electrode of the transistor.

It is still another object of the presentinvention' to provide new and improved apparatus which utilizes the base-emitter junction of the transistor. When the latter occurs, a negative voltage is produced at the collector electrode of the transistor. The voltage is approximately 0.5 volts and is of a high impedance, but is sufficient for constructive use, such as, for example, in an automobile voltage regulator-according to the invention.

A voltage regulator of the last described type employs the single transistor device to hold off a silicon controlled rectifier having a low gate current requirement. The voltage applied to the emitter of the transistor device, either from the battery or alternator output winding of the vehicle, controls the output voltage at the collector which is used to control the conductivity of the SCR through which excitation current is supplied to the field winding of the alternator.

DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is an enlarged symbolic view of a semiconductor junction transistor connected according to the invention to provide an output voltage of a polarity different than the voltage applied to the input thereof; and

FIG. 2 is a schematic diagram of a vehicle voltage regulator arrangement employing a transistor device of the above-described type.

DETAILED DESCRIPTION Referring now to the drawing in greater detail wherein like numerals have been used throughout the various views to designate similar components, there is shown in FIG. 1 a transistor 10 of the NPN type having base, emitter and collector portions 12, 14, 16, respec tively, comprised of either N or P type semi-conductor material as indicated.

Applied across the emitter-base electrodes 20, 22, respectively, extending from the respective portions of the transistor device, is a voltage of a first polarity derived from battery 18. A typical exampleof an NPN transistor of the type used in this case is a Motorola 791. With the last-mentioned transistor, a voltage of approximately +6 volts is applied across emitter-base electrodes 20, 22. Because the emitter is at a voltage level sufficiently higher than the base of the transistor, which in the case illustrated is at ground potentiaLthe emitter-base junction 24 of the device experiences a zener action or as is commonly termed, an avalanced condition occurs thereat. During the time the lastmentioned condition is occurring, it has been observed that a voltage is present at the collector electrode of the transistor which is of a polarity opposite from that applied across the emitter-base electrode of the device.

In the case of the .transistor example given heretofore, a negative one-half volts has been recorded at the collector electrode. The voltage at the collector elec' trode, although provided by a relatively high impedance source, represents a suitable inversion of the batteryvoltage applied at the input of the transistor and is sufficient for useful applications. To provide a lower impedance voltage source, a transistor having a larger emitter area; i.e., greater amount of semi-conductor material making up the emitter of the transistor, can be used. The latter produces, also, higher current flow.

Turning now to a consideration of FIG. 2 of the drawings, there is illustrated therein a one transistor voltage regulator circuit for use for example, in regulating the battery voltage in a motor vehicle.

The regulator circuit embodiment 30 of the drawing which is designed for use with a negative grounded automotive electrical system, employs a transistor of the NPN type having base, collector and emitter electrodes 34, 36, 38, respectively. The emitter electrode is coupled through a resistor 40 to the positive terminal of a storage battery 43 of the vehicle and via a resistor 42 to ground. The negative terminal 45 of the battery is grounded. The resistor arrangement serves as a voltage divider to apply a voltage across the emitter-base electrode of the transistor for operation thereof according to the invention. This will be explained hereinafter in greater detail.

Coupled via lead 44 to the collector or output electrode of thetransistor 32 is the gate electrode 46 of a silicon controlled rectifier (SCR) element 48; The anode 50 of the SCR is connected to the field winding 52 of an alternator device 54, shown in dashed lines.

The field winding 52 of the alternator is in turn connected directly to one phase winding 58 of the three phase windings 58, 60, 62, of the stator or output of the alternator device 54. A conventional rectifier bridge arrangement 64 is coupled to'the output phase windings also to provide rectified voltage to the vehicle electrical system and for charging the battery 43. A high impedance resistor 63, on the order of greater than approximately k ohms is connected between an output lead 61 of the rectifier arrangmement 64 and the gate electrode 46 of the SCR 48.

In operation, when the battery voltage is at a predetermined voltage level, the voltage applied across the emitter-base electrodes of transistor 32 is sufficient to maintain the emitter-base junction in an avalanched state-Thus, a negative voltage (opposite from the po- I larity of that voltage applied across the emitter-base electrodes 34, 38) is provided at collector electrode 36. This negative voltage is applied at the gate electrode 46 of SCR 48 to hold the latter in an open condition, overcoming the positive voltage provided by resistor 63 from the output of the alternator. No excitation current is provided from the output phase winding 58 of the alternator with the transistor 32 in the last-mentionedv condition. I

Upon the voltage level of the vehicle battery dropping sufficiently to overcome the avalanced condition of the emitter-base junction of transistor 32, the opposite polarity voltage at collector 36 ceases to exist. At

that time, SCR 48 is forward biased by the positive voltage from'resistor 63 and excitation current is provided from phase winding 58-to field winding 52. This in'turn causes the alternator device to produce charging current, to the vehicle'battery and raise the voltage level thereof to a point whet-eat the cycle repeats itself.

Thus, the discovered transistor phenomenon according to the invention can be applied to a voltage regulator device for an automotive vehicle, using only a single transistor element and a silicon controlled rectifier.

Other applications are also possible with the one transistor voltage transformation device. They will be apparent to those skilled in the art.

It will also be apparent to one skilled in the art that by providing a transistor of an opposite type; i.e.', PNP, a positive output voltage can beprovided by the application at the emitter-base junction of a negative polarity voltage capable of avalanching .the emitter-base junction of the transistor. The latter type of transistor canbe used in a regulator designed for an automotive electric system having the positive terminal grounded. While a particular embodiment of the invention has i been shown and described, it should be understood that the invention is not limited thereto since many modifications may be made. It is therefore contemplated to cover by the present application any and all such modifications as fall within the true spirit and scope of the and non-conductive states for controlling the excitation current provided by said output winding means of said generating device to said field winding means, a one transistor voltagesource coupled to the control electrode of said semi-conductor device for controlling the operation thereof between said states, said transistorincluding emitter, collector and base electrodes and means coupled electrically between said vehicle battery and said emitter electrode for applying across said emitter and base electrodes a voltage potential of a first polarity, the value of said firstpolarity voltage depending upon the voltage level of said battery and the output electrode of said transistor being coupled electrically to the control electrode of said semi-conductor device, the emitter-base junction of said transistor being placed in an avalanched state in response to the voltage level of said battery being at apredetermined level, thereby providing at the collector of said transistor a voltage of a polarity opposite from that applied at thev emitter-of said transistor to the controlelectrode of said semiconductor device for maintaining said device in a nonconductive state and said emitter-base junction being a removed from said avalanched state in response to the voltage level of said battery falling to a lower predetermined level, thereby removing said opposite polarity voltage from the control electrode of said .semiconductor device to permit the latter to be operated to a conductive state. I

2. A voltage regulator as claimed in claim 1 wherein said transistor is of the NPN type, wherein the voltage applied across said emitter-base junction is of a positive polarity of a predetermined magnitude and wherein the voltage applied to the control electrode of said semiconductor device is of a negative polarity and of a mag nitude less than that of said input voltage.

3. A voltage regulator as claimed in claim 1 wherein said semi-conductor device includes a silicon controlled rectifier having anode, cathode and gate electrodes and wherein the collector of .said transistor is connected electrically to the gate electrode of said silicon controlled rectifier. 

1. In a voltage regulator system for charging a storage battery in an automotive vehicle including an electrical power generating device having output winding means and field winding means coupled together electrically and a controlled semi-conductor device having input, output and control electrodes connected at one of said input and output electrodes to said field winding, said semi-conductor device being operable to conductive and nonconductive states for controlling the excitation current provided by said output winding means of said generating device to said field winding means, a one transistor voltage source coupled to the control electrode of said semi-conductor device for controlling the operation thereof between said states, said transistor including emitter, collector and base electrodes and means coupled electrically between said vehicle battery and said emitter electrode for applying across said emitter and base electrodes a voltage potential of a first polarity, the value of said first polarity voltage depending upon the voltage level of said battery and the output electrode of said transistor being coupled electrically to the control electrode of said semiconductor device, the emitter-base junction of said transistor being placed in an avalanched state in response to the voltage level of said battery being at a predetermined level, thereby providing at the collector of said transistor a voltage of a polarity opposite from that applied at the emitter of said transistor to the control electrode of said semi-conductor device for maintaining said device in a non-conductive state and said emitter-base junction being removed from said avalanched state in response to the voltage level of said battery falling to a lower predetermined level, thereby removing said opposite polarity voltage from the control electrode of said semi-conductor device to permit the latter to be operated to a conductive state.
 2. A voltage regulator as claimed in claim 1 wherein said transistor is of the NPN type, wherein the voltage applied across said emitter-base junction is of a positive polarity of a predetermined magnitude and wherein the voltage applied to the control electrode of said semi-conductor device is of a negative polarity and of a magnitude less than that of said input voltage.
 3. A voltage regulator as claimed in claim 1 wherein said semi-conductor device includes a silicon controlled rectifier having anode, cathode and gate electrodes and wherein the collector of said transistor is connected electrically to the gate electrode of said silicon controlled rectifier. 